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background    feedstocks    processes    products

Wisconsin raises over 3 million cattle, 500,000 hogs and 5 million chickens annually.¹ It is one of 12 states whose production of raw and dressed meat—known as first processing—generates shipments in excess of $1 billion annually. Wisconsin's further processing industry is ranked first in the nation for both shipments and added value.²

First processing begins in the slaughterhouse. Slaughterhouse operations receive and hold live animals for slaughter. The animals are then stunned prior to slaughter, bleeding and hide or hair removal. It is commonly said that "everything but the squeal" finds its way to the market. Careful handling and controlled rendering of animal byproducts are crucial to the production of some animal feeds. For instance, hog hair extracted from dehairing machines on the kill floor is often hydrolyzed and cooked for inclusion in animal feed.

The manufacture of fine leather products starts at this stage with the soaking, dehairing and bating of cowhide. The harvest of variety meats, such as sweetbread, liver and tongue, takes place during first processing, as do some cutting, deboning and grinding operations. The reduction of whole or split carcasses into quarters or smaller segments in preparation for further processing is usually considered to be part of first processing. These fractions, along with large quantities of ground meat, are packaged and refrigerated until and during shipment.

Further processing is sometimes conducted at the same facility as first processing. First, the carcass halves or quarters is broken into more manageable sizes for handling. Unwanted fat is trimmed at this stage and stored in drums for renderer pick-up. Rendering processes inedible tallow and grease into soaps, feeds, lubricants and other products. In the cutting operation, larger pieces of meat are cut or sawed for the direct marketing of the smaller sections or individual cuts, or for further processing in the production of processed meat products. Further processing operations may continue through sausage production, curing, pickling, smoking, cooking and canning.

First processing for poultry typically involves more steps than for meat. Blood and feathers collected from first processing are often used in the production of animal feeds. Further processing can be as simple as splitting a poultry carcass into two halves or as complex as producing a breaded, fully cooked product.

• Beef tallow
• Edible offal
• Inedible offal
• Manure (dairy)
• Manure (swine)
• Manure (poultry)
• Scrap/spoilage (meat packing)
• Wastewater (meat packing)

• Aerobic digestion/composting
• Anaerobic digestion
• Biomass gasification
• Combustion
• Esterification/transesterification
• Lipid extraction
• Thermochemical liquefaction
• Vitrification

• Anaerobic digestion effluent
• Biobased fuel gas & syngas
• Bio-derived liquefaction oil
• Biodiesel
• Biogas
• Char
• Fertilizer
• Glass aggregate
• Glycerin
• Specialty chemicals
• Volatile gases (energy)

[1] Wisconsin Agricultural Statistics Service. Wisconsin's Rank in the Nation's Agriculture, 2002. (16 April 2004)

[2] Whitman, Christine, et al. 2002. Development Document for the Proposed Effluent Limitations Guidelines and Standards for the Meat and Poultry Products Industry Point Source Category (40 CFR 432) . U.S. Environmental Protection Agency Office of Water , Washington, DC. (16 April 2004)

Wolff, Ivan A. Ed. 1982. CRC Handbook of Processing and Utilization in Agriculture: Vol. I Animal Products. Boca Raton, FL.